1. Field of the Invention
The present invention relates to a seat structure having an air bag apparatus for a side impact (hereinafter referred to as a "side impact air bag apparatus"), and more particularly to a seat structure which has a side impact air bag apparatus at a side portion of a seat back frame.
2. Description of the Related Art
A seat structure having a side impact air bag apparatus has been conventionally known, and Japanese Patent Application Laid-Open (JP-A) No. 4-50052, U.S. Pat. No. 5,348,342, U.S. Pat. No. 5,112,079, U.S. Pat. No. 5,222,761, U.S. Pat. No. 5,251,931, U.S. Pat. No. 5,498,030, etc., disclose such a seat structure. Among them, Japanese Patent Application Laid-Open (JP-A) No. 4-50052 discloses a seat structure in which a folded air bag is accommodated in a concave portion formed in a side portion of a seat base member. FIGS. 7 and 8 show an example of such a seat structure having a side impact air bag apparatus.
In the seat structure shown in FIG. 7, an air bag apparatus 74 is disposed within a side portion 72A of a seat back 72.
As shown in FIG. 8, the air bag apparatus 74 has a box-like shape whose longitudinal direction coincides with the vertical direction of the vehicle, and is attached to a side frame (i.e., reinforcing member) 80 of a seat back frame 78 using screws 83.
As shown in FIG. 7, a lid portion 82A is disposed opposite to the side frame 80 with respect to an air bag case 82. When the air bag 84 is expanded, the lid portion 82A opens outward in the widthwise direction of the seat (in the direction of arrow W in FIG. 7) around a hinge portion 82B formed at the rear end in the longitudinal direction of the vehicle. Moreover, upon opening of the lid portion 82A, a seat surface layer 86 is ruptured.
However, the above-described seat structure having a side impact air bag apparatus has the following problems.
(1) Since the air bag apparatus 74 is attached to the outer side surface 80A of the side frame 80 in the transverse direction of the vehicle, the overall width of the seat back 72 increases. PA1 (2) Since the air bag apparatus 74 projects from the side frame 80 further toward the rear of the vehicle than the seat back, the thickness of the side portion 72A of the seat back 72 in the longitudinal direction of the vehicle also increases.
Accordingly, the effective room space of the vehicle decreases.